libpgagroal: utils.c: fix UB in pgagroal_read_int32()

In pgagroal_read_int32, the byte[i] value is promoted to int32.
According to the C spec, if you cannot represent the result
in the result type, then that behavior is undefined (6.5.7).

This issue is fixed by explicitly casting the bytes[i] values
to uint32_t.

Signed-off-by: Henrique de Carvalho <decarv.henrique@gmail.com>

Author: decarv

src/libpgagroal/utils.c

@@ -316,10 +316,10 @@ pgagroal_read_int32(void* data)
                             *((unsigned char*)(data + 2)),
                             *((unsigned char*)(data + 3))};
 
-   int32_t res = (int32_t)((bytes[0] << 24)) |
-                 ((bytes[1] << 16)) |
-                 ((bytes[2] << 8)) |
-                 ((bytes[3]));
+   int32_t res = (int32_t)(((uint32_t)bytes[0] << 24)) |
+                 (((uint32_t)bytes[1] << 16)) |
+                 (((uint32_t)bytes[2] << 8)) |
+                 (((uint32_t)bytes[3]));
 
    return res;
 }